Methods and systems for quantitative colorimetric capnometry

Abstract

Quantitative colorimetric carbon dioxide detection and measurement systems are disclosed. The systems can include a gas conduit, a colorimetric indicator adapted to exhibit a color change in response to exposure to carbon dioxide gas, a temperature controller operatively coupled to the colorimetric indicator and configured to control the temperature of the colorimetric indicator, an electro-optical sensor assembly including a light source or sources adapted to transmit light to the colorimetric indicator, and a photodiode or photodiodes configured to detect light reflected from the colorimetric indicator and to generate a measurement signal, and a processor in communication with the electro-optical sensor assembly. The processor can be configured to receive the measurement signal generated by the electro-optical sensor assembly and to compute a concentration of carbon dioxide based on the measurement signal. Methods for using the systems are also disclosed including providing a breathing therapy to a patient or user.

1 . (canceled) 
     
     
         2 . A method for treating PTSD, comprising:
 sampling, via a nasal cannula and associated sensor, a respiratory gas stream from the user, wherein the respiratory gas stream is coupled to a test unit configured to measure respiratory parameters of the user, wherein the respiratory parameters include the respiratory rate of the user and end-tidal CO 2  level of the user corresponding to carbon dioxide levels in the gas stream from exhalation of the user;   converting the respiratory parameters to measurement signals via an electro-optical sensor assembly of the test unit coupled to the associated sensor via the nasal cannula;   displaying, at a display of the test unit, the measurement signals representing the respiratory parameters;   instructing the user, via audio and visual cues outputted at the display of the test unit, to control the respiratory rate of the user based on a breathing protocol configured to achieve one or more of the target end-tidal CO 2  levels and target respiratory rate for the user; and   achieving, via the breathing protocol, the one or more of the target end-tidal CO 2  levels and target respiratory rate for the user.   
     
     
         3 . The method of  claim 2 , wherein displaying, at the display of the test unit, the measurement signals representing the respiratory parameters, includes displaying a visual pacing of rising and falling visual indicator bars configured to represent the respiration rate of the user in real-time. 
     
     
         4 . The method of  claim 2 , wherein instructing the user, via the display, to control the respiratory rate of the user based on the breathing protocol includes providing, at the display, a visual pacing of rising and falling visual indicator bars configured to serve as the breathing protocol, further wherein the user controls the respiratory rate of the user to mirror the visual pacing configured to serve as the breathing protocol to achieve the one or more of the target end-tidal CO 2  level and the target respiratory rate for the user. 
     
     
         5 . The method of  claim 3 , further comprising synching the visual pacing with the audio cues outputted by the display of the test unit. 
     
     
         6 . The method of  claim 2 , wherein measuring the respiratory parameters indicates a disease-disorder state including one or more of: PTSD, panic disorder, anxiety, asthma, hypertension, obsessive-compulsive disorder, social phobia, depression, apnea, migraines, and epilepsy. 
     
     
         7 . The method of  claim 2 , wherein achieving and maintaining the one or more of the target end-tidal CO 2  levels and the target respiratory rate for the user is configured to treat a disease-disorder state including: PTSD, panic disorder, anxiety, asthma, hypertension, obsessive-compulsive disorder, social phobia, depression, apnea, migraines, and epilepsy. 
     
     
         8 . The method of  claim 2 , wherein controlling the respiratory rate of the user based on the breathing protocol uses the respiratory rate of the user as a biomarker. 
     
     
         9 . The method of  claim 2 , further comprising computing, via a processor, one or more of: the end-tidal CO 2  level of the user and the respiration rate of the user from the respiratory gas stream of the user, pursuant to the processor receiving the signals from the electro-optical sensor assembly of the test unit. 
     
     
         10 . The method of  claim 2 , further comprising prompting the user for a specified breathing rate and breathing volume pattern as part of the breathing protocol. 
     
     
         11 . A method for PTSD treatment, comprising:
 measuring a user's respiratory parameters including a respiratory rate of the user and an end-tidal CO 2  level of the user based on exhaled carbon dioxide of the user;   instructing the user to control the respiratory rate of the user and an inspiratory volume of the user based on a breathing protocol configured to achieve one or more of a target end-tidal CO 2  levels and a target respiratory rate for the user via one or more of: (i) visual pacing of rising and falling visual indicator bars configured to represent the respiration rate of the user in real-time and (ii) respiratory feedback;   the user practicing the instruction based on the breathing protocol to achieve the one or more of the target end-tidal CO 2  level and the target respiratory rate for the user; and   the user achieving the one or more of the target end-tidal CO 2  level and the target respiration rate for the user.   
     
     
         12 . The method of  claim 11 , further comprising the user practicing the instruction based on the breathing protocol to achieve the one or more of the target end-tidal CO 2  level and the target respiratory rate for the user via the user following one or more of the audio and visual cues. 
     
     
         13 . The method of  claim 12 , further comprising the user maintaining the instructed control of the respiratory rate of the user based on the breathing protocol after the user achieves the one or more of the target end-tidal CO 2  level and the target respiration rate for the user, in order to maintain the target end-tidal CO 2  level in the exhaled carbon dioxide of the user. 
     
     
         14 . The method of  claim 11 , wherein measuring a user's respiratory parameters occurs during a baseline stage, further wherein instructing the user to control the respiratory rate of the user based on the breathing protocol occurs during a pacing stage, and still further wherein the user practicing the instruction based on the breathing protocol occurs during a practice stage. 
     
     
         15 . The method of  claim 11 , wherein the respiratory feedback includes monitoring one or more of the end-tidal CO 2  level of the user and the respiration rate of the user. 
     
     
         16 . The method of  claim 11 , further comprising:
 communicating the user's respiratory parameters to one or more of a device and a dataset;   performing an algorithm to assess for the breathing protocol configured to achieve one or more of a target end-tidal CO 2  level and a target respiratory rate for the user; and   instructing the user to control the respiratory rate of the user based on the breathing protocol.   
     
     
         17 . The method of  claim 12 , wherein the user following one or more of the audio and visual cues includes the user following audio tones configured to assist the user pace the respiratory rate of the user with the breathing protocol. 
     
     
         18 . The method of  claim 17 , further comprising the user following the audio tones to achieve a target number of breaths per minute for a therapy session. 
     
     
         19 . The method of  claim 11 , wherein instructing the user to control the respiratory rate of the user based on the breathing protocol configured to achieve the one or more of the target end-tidal CO 2  level and the target respiratory rate for the user includes the user following breathing cues to adjust a volume of air inhaled by the user to match a target volume of breath to be inhaled by the user. 
     
     
         20 . The method of  claim 19 , wherein the user reduces the volume of air inhaled by the user based on the breathing cues to treat a disorder of the user including PTSD, panic disorder, anxiety, asthma, hypertension, obsessive-compulsive disorder, social phobia, depression, apnea, migraines, and epilepsy. 
     
     
         21 . The method of  claim 3 , further comprising guiding the user based on displaying the visual pacing with visual breathing guidance, wherein the visual breathing guidance includes visual representations indicating one or more of: (i) a target length of inhalation for the user, (ii) a target length of exhalation for the user, and (iii) a target length of pauses in between the inhalation and the exhalation, further wherein the user follows the visual breathing guidance to achieve or maintain the one or more of the target end-tidal CO 2  level for the user and the target respiratory rate for the user.